FORMATION OF AGGREGATES 277 



but absorption only during phosphorescence would 

 imply a change in the molecular structure of 

 the gas. 



In the case of fluorescent bodies they un- 

 doubtedly are formed, whilst the destructive action 

 of infra-red rays shows that they can also be 

 made to break down more easily when the 

 aggregation exceeds a certain size. 



